Ah, the warp-speed leap into adolescence! The brain reorganizes at that age, and it turns kids surly and, sorry to say, a little dumber. Ask any sixth-grade teacher what it's like to get productive work out of a 12-year-old. One of my boys turned angry, sarcastic and dumb; the other got surly, sarcastic and dumb. Forgotten assignments, inability to focus, withering criticism about every darn thing — oh, it's a blast. Deal with the bad behavior, decide how much sass you're willing to endure, enforce consequences and ride out the storm.

This morning, my almost 12-year-old chewed me out about a sweater before I even got out of bed. In part, yes, you've got to just ride it out. But also be sure to let him know when his mood and behavior are unpleasant to others in the family. A little good-natured teasing can lead to the tween seeing himself as others see him, starting to make fun of himself in this regard, and (one hopes) even working to modify the behavior a bit.

"I talk to people all the time who say, 'What happened to the sweet, bubbly boy we knew when he was 10?'" says neuroscientist and clinical psychologist Scott Swartzwelder, co-author of the upcoming book, "What Are They Thinking?! The Straight Facts About the Risk-Taking, Social-Networking, Still-Developing Teen Brain" (Norton).

A lot of things are happening to him, of course. The question is whether his surly reaction is cause for alarm.

"Most of the people assessing normality and abnormality are adults," Swartzwelder says. "And most adults tend to remember what they did when they were adolescents, but they forget how they felt."

That's worth bearing in mind as you consider your son's mood.

Also worth remembering? "You know your kid better than anybody else," Swartzwelder says. "You could take him to a doctor or a psychologist and they're going to look for sets of symptoms and make a judgment based on their clinical awareness of the average kid. And that's OK. That's how medicine works.

"But parenting has an advantage over medicine in that you know your kid."

Watch for signs that he's suffering more than a typical amount of adolescent angst: "A funk that lasts more than a week or two or seems to be getting worse rather than better," Swartzwelder says. "Losing interest in things that used to interest him a lot. Complete changes in his circle of friends. Marked shifts in sleep patterns. If he starts to lose weight or gain weight."

And don't be afraid to ask him about his feelings.

"Find ways to slip questions into your conversations that get at how things are going," Swartzwelder suggests. "'I've noticed you've been a little quieter lately. Everything OK?' Don't push too hard, but don't back off.

"You want to plant those little seeds that remind him, 'Hey, I care about this issue, but even more, I care about you.' Then if your kid really starts feeling bad, he knows you're there and you're not going to freak out or be judgmental."

Have a solution? Your daughters have very different body types — one tiny, one husky. How do you minimize the constant comparing? Find "The Parent 'Hood" page on Facebook, where you can post your parenting questions and offer tips and solutions for others to try.